Composition comprising alkenyl aromatic resin and hexachlorocyclopentadiene-divinylbenzene adduct and process for preparing



. polymerizable alkenylaromatic compounds.

" polymeric-resin comprisesin chemically combined form at least50 percent by weig'htofat least one alkenyl aromatic compound having th'e general formula:

, in the composition. i

[coMPos'Irro commsiNjo ALKE'NYL' not, MATIC nnsm AND nExAcnLoRocYcLornm 'lADllINE-DIVINYLBENZENE. ADDUCT AND PROCESS FORsPREPihRlli 1 Carleton W. Roberts, Midland, 'hiich assignor to The Dow Chemical Company, Midland, Micln, a corporation of Delaware This invention concerns' polymeric compositions of matter comprising thermoplasticalkenyl aromatic resins having intimately incorporated therewith the adducts of hexahalocyclopentadiene and divinylbenzene which im- 2,967,842 Patented Jan. 10, 1961 'ice -corporating certain bromine-containing organic compounds .with alkenyl aromatic resins. Most organic alkenyl aromatic resins for the reasons that it is necessary to employ the chlorine-containing compounds in-- parts fiame retardance tolthecomp'ositions. It relates 'more particularly to' compositions of alkenyl aromatic resin and mixtures of meta and para-bis(1',4,5,6,7,7-,

hexachlorobicyclo. [2.2.l-]-5-hepten-2-yl)benzene which possess flame retardant properties and pertains to a methodof making the compositions.

By an alkenyltaro'matic resin" is meant a solid resin containing in chemicallyv combined form one or more I The wherein Ar represents an aromatic hydrocarbon radical,

or anaromatic haiohydrocarbon radicalp'of, the benzene series and 'R ishydrogen-or the-methyl radical. Examples other readily polymerizable olefinic compounds such as acrylonitrile, methyl methacrylate or, the like; solid copolymers of one or moreof su'ch'alkenyl aromatic compounds'iandfroml to 15 percent by weight of natural or a synthetic rubber; and resinous compositions, e.g.

mechanical blends, of such polymers'and synthetic rubber intimately incorporated with one another and containing a totalof not more than 35 percent by weight of rubber Theterm flame-proof" as employed herein means incapable of burning or sustaining a flame for more than 15 seconds after a composition has been fully heated in an open flame and then removed from the flame used to heat the-same. In other words the flame-proof compositions are self-extinguishing after'removal from a flame used to heat the same. a

It is known that the halogen content of halogenated organic compounds often has an effect of reducing the flammability both of the compound containing the halogen and of: flammable organic materials intimately admixed therewith. It is also known that bromine-containing compounds, possess, in most instances, a greater flame retarding action than do corresponding chlorine-containing compounds. There are numerous instances in which the flammability of organic materials such as wood, paper,

' cellulose derivatives, plastics and the like has been reduced by admixing organic halogen-containing *compounds therewith. For example, US. Patent No. 2,723,-

agents, including organic bromides, have an eifect of impairing to some extent one or more of the properties, eig. of reducing the tensile. strength, impact strength or 'heat distortion temperature, of polystyrene or other alkenyl aromatic resinswhen incorporated with the resin.

This effect becomes greater as the proportion of such addition agent is increased. Since the chlorine-containing organic compounds possess, in most instances, a lesser flame-retarding action than do corresponding brominecontaining compounds, they have not heretofore been found practically elfective for the flame-proofing of greater proportions and this results in greater impairment of the properties of the resin. It is also desirable that the organic chloride be' compatible with such alkenyl aromatic resin so that it can uniformly be incorporated withthe latter to obtain a non-flammable composition of good appearance.

It has now been found that the adducts or addition "reaction productsof hexachlorocyclopentadiene and diviny lbenzene areelfective in flame-proofing and in inhibitin'g burning of alkenyl aromatic resins when admixed therewith inminor amount, e.g. inarnount of v50 percent by weight or less of the composition. It hasfurther been found that these adducts, namely, metaand parabis-( 1,4,5,6,7,7-hexachlorobicyclo[2.2.1] 5 hepten-Z- yl).benzene, are compatible with the alkenyl aromatic resins in amount sufficient to render the resins flamep'roof, and when added in such amount, e.g. from about 20 to 35 percent by weight, based on the sum of the weights of the resin and said added agent, do not seriously impair the appearance or properties of the resin. Lesseramounts of the adducts, e.g. from 5 to 15 percent by weight,'substantially inhibit burning of the composition and have a lesser effect on the properties of the resin.

It has also been found that the alkenyl aromatic resin compositions comprising the metaand para-bis(l,4,5,6,

7,7-hexachlorobicyclo[2.2.1] 5 heptene-Z-ylbenzene More specifically, the organic chlorides are the reaction I product of hexachlorocyclopentadiene with mctaor paradivinylbenzene, preferably a mixture of metaand paradivinylbenzene. The compounds are the addition reaction product of two gram molecular proportions of hexacholorocyclopentadiene with one gram molecular proportion of divinylbenzene and have the formula:

wherein the bicycle radicals are attached to the benzene 9.63 makes non-flammable plastic compositions by innucleus in positions metaor parato one another. The adducts can be prepared by procedure described in my co- 3 pending application Serial No. 717,812. filed on even date herewith. In brief. metaand para-bis(1,4,5,6,7,7-hexachlorobicyclo [2.2.l]-5-hepten-2-yl)benzene can be prepared by reacting hexachlorocyclopentadiene with a mixture of metaand para-divinylbc'nzene at temperatures" between about 70 and 120 C.', while having the re-f actants dissolved in an inert liquid inorganic solvent such as n-heptane or toluene. Upon completing the reaction a portion'of the solvent is removed bydistilling. and the residue is cooled to crystallize the product. When employing a commercial grade ofdivinylbenzene as the startingmaterial, which divinylbenz'ene is usually a mixture of the. meta-.andpara-isomersythe product is obtained as a white crystallinematerial melting at temperatures between'about' 150 and'180 C. depending in partup'on.

mixer or in a plastics extruder to cause thorough and uniform distribution of the ingredients with one another. If desired, the alkenyl aromatic resin can be heated and milled or the flame-proofing agent and the resin can be dissolved in a mutual solvent such as toluene, xylene or ethylbenzene and the solvent thereafter be distilled or vaporized from the solution. Other addition agents such I as pigments, antioxidants, stabilizers, plasticizers, fiow I agents, lubricants and the like may also be incorporated in the plastic composition by any of the foregoing 'procedures, but are not required. The compositions of the invention are flame-retardant,

" i.e. they burn slowly, or are flame-proof or self-extinguishthe relative proportions o f,the-meta-' and para=bis(l,4,5,-

6,7,7 hexachlorobieyclo [2.2.1] 5-hepten-2-yl) benzene j isomers in the mixture. The pure meta;and para-iso meric compounds canb'e'separate'dfrom the mixture inv usual ways; e.g.. byfractional crystallization, and have been found to have melting points that are above the melting point of mixtures of the isomers. The compound 2 -yl)-benzene has been found tohave a melting point of from about 2l0-2l5 C.-,- and para-bis(1,4,5,6,7,7 hexachlorobicyclo [2.2.1]-5-hepten 2-yl)benzcne melts at about 285-292 C.

-meta-bis-(l,4,5,6,7,7-hexachlorobicyclo [2.2.11-5-hepten- The pure compoundshaving'rneltingpoints within the 7 ranges stated can beemployed as flame-proofing agents in alkenyl aromatic resin. compositions, but for practical employment with the alkenyl aromatic resins, mixtures of the aforementioned isomeric l'lflfita'. and para-compounds, which mixture 'ha's 'a' melting point within the range of from 150 to 180C, are preferred:- Such mixtures of the metaand para-flame-proofing compounds are stable against decomposition at usual molding temperatures of from 140v or l'ower to 225 C. or thereabout,'employed for the processing, e.g. the manufacture of molded or extruded articles, of alkenyl aromatic resins,

a and because of their. compatibility with the resin and liquid condition at the molding temperatures have a substantial plasticizing action for increasing the rate of flow ofthe'heat-plastified resin.

The metaand para-bis(l,4',5,6,7,7-hexachlorobicyclo [2.2.'1]-5-hepten-2-yl)benzene can be employed in amounts of from about 5 to 50, preferably from 5 to 35, percent by weight, based on the sum of the weights of the In general, compositions comprising from 85 to acne are substantially resistant to- ,burning, i.e. burn very slowly or not at all, whereas compositions comprising i from 65 to 80 percent by weight of the alkenyl aromatic resin and from 20 to percent of said compounds are self-extinguishing or flame-proof.

erably from 65 to 95 parts by weightof afiammable al- .kenyl aromatic resin such as polystyrene, a copolymer of styrene and alpha-methyl styrene, a copolymer of styrene and acrylonitrile or a copolymer of styreneand from 2 to 15 percent by weight of a synthetic rubber, e.g. a rubbery copolymer of butadiene and styrene. Incorporation of the agent withthe alkenyl aromatic resin can be accomplished in anumber of ways. In most instances, a nonuniform mechanical mixture of the resin and the flame p'roofingagent is heated to a plastifying' temperature between about 120 and 220 C. or above and the heated mixtureis milled or compounded on rolls, a Banbury 'ing'. They can be molded-orextruded to obtain articles which are flame-proof or flame-retarding. The compositions are useful for a variety of purposes. They can be molded to form boxes, film, sheet, or plates.

The following examples describe a number of ways for practice .of the invention and illustrate certain of its advantages, but are not to be construed as limiting its scope.

EXAMPLE -1 A purpose of this example is to show the preparation of. the hexachlorocyclopentadiene-divinylbenzene adduct employed'as flame-proofing agent in the compositions'of the invention. v

;A charge of 1700 grams of -hexachlorocyclopentadicue, together with 1500 ml. of toluene as solvent and re- 1 action medium were placed, in a glass reaction vessel equipped with a reflux condenser and stirrer. The m1x-.

ture was stirred and heated to its reflux temperature, about 119 C. A charge of 9100 grams of a commercial grade of divinylbenzene containing '55 percent by weight of isomeric metaand para-divinylbenzene was added slowly over a period of 45 minutes. The resulting mixture was stirred and heated at its reflux temperature for .4 hours, Thereafter, a major portion of the toluene was removed by heating the mixture under reduced pressure and distilling off the toluene. The distillation was continu'ed until the residue in the reaction vessel was being heated 'at a temperature of 140 C. at 10 millimeters absolute pressure.- The residue was cooled to about 100 'C. and was poured into 4 liters of n-hexane with stirring. .The resulting mixture was cooled in an ice bath. A

crystalline material separated from the liquid; The crystals were separated by filtering and were washed and dried. There was obtained 1200 grams of a white crystalline material melting at temperatures between and C. This material was recrystallized from a mixture of one part by volume of toluene and three parts by volume of n-heptane and was washed and dried. There-was obtained 1000 grams of a white crystalline product, melting at temperatures between 174 and 177 C. The product was a mixture of isomeric meta-and para bis(1,4,5,6,7,7 hexachlorobicyclo[2.2.11-5-heptcn- 2-yl) benzene.

EXAMPLE 2 In each of a series of experiments, a charge of 300 grams of a mixture of a resinous copolymer of 75 percent by. weight of styrene and 25 percent of alpha-methyl styrene and the metaand para-bis(l,4,5,6,7,7-hexachlorobicyclo [2.2.l]-5-hepte n 2 yl)benzene melting at 174-177 C., prepared in Example 1, in proportions as stated in the following table was compounded on heated laboratory rolls at a temperature of 180 C. for a period of 6 minutes to obtain a uniform composition, then was removed, allowed to cool and was ground to a granular form suitable for molding. Portions of the composition were injection molded to form test pieces of Vs x /s inch cross-section. These test pieces were used to determine a tensile strength and percent elongation value for the composition employing procedures similar to those described in ASTM'D638-49T. Impact strength was determined on molded test pieces of /s x /2 inch i 5 cross eection by procedure similar to that described in ASTM D25647T. Other molded. test pieces of the The compositions had properties as follows:

A composition w'asprepared by compounding a mixture of 75 parts by weight of a resinous copolymer of '75 percent by weight of styrene and 25- percent of amethyl styrene, and 25 parts by weight of a mixture of metaand para-bis- (1,4,5,6,7,Whexachlorobicyclo [2.2.1]-

S-hepten-Z-yDbenZene, similar to that described in Example l, on heated rolls ata temperature of 180 C. for a period o.6 minutes. Portions of the composition were molded and'tested employing procedures similar to those employed in Example composition of A: x bi inch cross-section were employed A B to determine a head distortion temperature employing a procedure similar to that ot'I-Ieirholzer and Boyer, see 5 Copolymenparts 15. Flamein 02 nt a t 25. ASTM Bull lflo. 134 of May 1945. A flammability or ggg i j t 4,8009 self-extinguishing property for the composition was de- Eio'uatlomperce i it 1. termined by procedure similar to that described in'ASTM Heat Dismal, en a C Fl b i l i D63544. ;Table I identifies thecompositions and gives 'amma f i m/mm h3g5. the proportions of the copolymer and the bis(l,4,5,6,7,7- o gleltvisgosltyrpmses-nolor Transv hexachlorobicyclo [2.2.11-5-hepten 2 1 yl) benzene emparent. parent.

ployed. in. preparing the same. The table also gives the properties determinedjor the product. The 'composi: tions we're transparent homogeneous products. In the EXAMPLE 4 table the term .he'xachlorocyclopentadiene-DVB vaddu'ct 15 In each of a series off-experiments, an alk enyl aromatic is employed to designate the bis('l,4,5, 6,7,7-hexachlororesin composition was prepared by milling a polymeric bicycio [2.2.11-5-hepten-2-yl) benzene, for brevity. material as identified in the following table and a mixture Table I Starting Materials Product Run Copol er Hexachioro- I i No. 0175., StY-eyriopenta- Tensile Elonga Notched Heat Burning rents-257 dleneDVB Strength, tion, Impact Distortion rate, u-m'ethy edduct, lbs./sq.ln. Pementf Strength, Tergp in./mln. styrene, Percent tt.-lbs. 9 Percent 100 9.000 3.4 0.20 9a 1.8 95 9.550 as 0.29 96 1.2 90 10' 8.030 26 0.20 93 1.2 85 1.770 a4 0.19 91 1.1 so 7.220 2.3 0.19 92 0.78 76 6.400 1.9 0.19 as 0.0 70 a0 6.160 1.3 0.18 86 0.0 05 5.380 1.0 0.20 83 0.0

EXAMPLE 3 of metaand para bis(1,4,5,6,7,7 hexachlorobicyclo [2.2.l]-S-hepten-2?yl)benzene melting at temperatures of 165 to 180 C. on compounding rolls at a temperature between 180 and 185 C. for a period of 6 minutes. Portions of the composition were molded and tested for heat distortion-temperature and flammability employing procedures similar to those employed in Example 2. Table identifies the compositions by naming the polymeric ingredient and gives the proportions of the same and the flame-proofing agent employed in making the same. The table also gives the flammability and heat distortiontemperature for the composition.

Table II Starting Materials Product Run No. Alkenyi Aromatic Resin Flame- Heat Disproofing tortton Flammabilitybumagent Temp tng rate, in./mln. Kind Percent Percent C.

1 Polystyren 95 5 bums slowly. 2 do; 90 10 o. 3 20 71 Self-extinguishing.

67 33 66 D0. 50 50 67 D0. 33 2 2( 86 n gulshin 89 e ex 11 75 25 87 D0. 8 65 35 82 D0. 85 15 85 1.13. 80 20 91 0.80. 75 25 selt extinguishing. 65 35 84 D0. blend of 75% Oopolymer of 70% St rene. 30% Acryloni- 85 15 91 0.90. trile and 25% rubber? copolymer of 60% utadiene, 20% Acrylonitriie, 20% methy isopropenyi ketone. 1 i5 o-.- 80 20 87 0.73. 16 do 75 25 86 0.72.

For purpose of comparison a charge of the copolymer EXAMPLE 5 of styrene and a-methyl styrene was milled on the compounding rolls for the same time and at the same temperature, then cooled, molded into test pieces and tested in the same manner.

In each of a series of experiments, a solid copolymer, prepared by polymerizing a solution of 95 parts by weight 75 of monomeric styrene and 5 parts of a synthetic rubber soluble in the monomer and containing in chemically combined form about 73.5 percent by weight of butadiene and 26.5 percent of styrene, in mass; was milled with a A B G copolymer, parts. Q5. Flameproofin a2 parts 35. Tensile strength, lbs./so.in- 5,210 Elon ation, perc'ent.--.' 5.3.

Notched impact strength, it.-l s 0.25.

Heat distortion temperature, C. 78 66.. Flammability"; burns seli-extinselt extinguishing. guishing.

EXAMPLE 6 A composition was prepared by milling 75 parts by weight of a resinous copolymer of 75 percent by weight of styrene and 25 percent of alpha-methyl styrene, and 25 parts by weight :of meta-bis(1,4,5,6,7',7-hexachlorobicyclo [2.2.1]-5-hepten-2-yl)benzene melting at 213 C.,

, on compounding rolls at-a temperature of 180" C. for a A B C copolymer, parts. 100 75 Para-adduct, parts. 25 Metn-adduct, parts 0 0 Tensile strength, lbs/sq. in". 8, 530 6, 910 7, Elongation, percent 3 2. 5 Note ied impact strength, it.-lbs 0. 20 0. 18 0. Heat distortion -temp., 08 90 Flammability rate, in./min 1.5

I Self-extinguishing.

EXAMPLE 7 A composition was prepared by milling 75 parts by weight of an alkenyl aromatic resin, consisting of an intimate blend of 75 parts by weight of a resinous copolymer of 70 percent by weight of styrene and 30 percent of acrylonitrile and 25 parts by weight of a rubbery copolymer of 60 percent by weight of butadiene, 20 percent of methyl isopropenyl ketone and 20 percent of acrylonitrile, prepared by heat-plastifying the resinous copolymer and the rubbery copolymer and mechanically working the polymeric ingredients into a uniform prod uct, and 25 parts by weight of para-bis(1,4,5,6,7,7-hexachlorobicyclo [2.2.1]-5-hepten-2-yl)benzene melting at 290 C. on compounding rolls at a temperature of 180 C. fora period of 6 minutes. Portions of the composition were molded and tested employing procedures similar to those employed in Example 2. The alkenyl aromatic resin starting material and the composition had the properties:

Aikenyl aromatic resin, parts 100 75 Pars-adduct, parts 0 25 Tensile strcngth,1bs./sq. tn 6, 260 Elon ation 2. 8 Notcned impact strength 0. 41 Heat distortion temperat 92 Flammability l Scliezttingulshing.

I claim:

.1. A flame-retardant composition of matter comprising an intimate mixture of from 50 to 95 percent by weight of an alkenyl aromatic resin comprising a solid flammable polymer containing in chemically combined 3 form at least 50 percent by weight of at least one aikenylaromatic compound having the general formula:

R Ar( J=CH:

wherein Ar represents an aromatic radical of the group consisting of hydrocarbon and halohydrocarbon radicals of the benzene series and R is a member of the group consisting of hydrogen and the methyl radical, and from 50 to 5 percent by weight of at least one halogen-containing organic compound selected from the group consisting of meta-bis(1,4,5,6,7,7-hexachlorobicyclo [2.2.1]- S-hepten-Z-yl) benzene, para-bis( 1,4,5 ,6,7,7-hexachlorobicyclo [2.2.1]-5-hepten-2-yl)benzene and mixtures thereof.

2. A composition as claimed in claim 1 wherein the alkenyl aromatic resin is polystyrene.

-3. A composition as claimed in claim 1, wherein the alkenyl aromatic resin is a copolymer of styrene and alpha-methyl styrene.

4'.'A composition as claimed in claim 1, wherein the alkenyl aromatic resin is a copolymer of from to 98 percent by weight of styrene and from 15 to 2 percent ofa rubbery copolymer of butadiene and styrene. 40

5. A composition as claimed in claim 1, wherein the alkenyl aromatic resin is a copolymer of approximately 70 percent by weight of styrene and 30 percent of acrylonitrile.

6. A composition as claimed in claim 1 wherein the halogen-containing organic compound is a mixture of metaand para-bis(l,4,5,6,7,7-hexachlorobicyclo[2.2.1]- 5-hepten-2-yl)benzene melting at temperatures between and C..

7. A non-flammable composition of matter comprising an intimate mixture of from 65 to 80 percent by weight of an alkenyl aromatic resin comprising a solid flammable I polymer containing in chemically combined form at least wherein Ar represents an aromatic radical of the group consisting of hydrocarbon and halohydrocarbon radicals of the benzene series and R represents a member of the group consisting of hydrogen and the methyl radical, and from 35 to 20 percent by weight of at least one halogencontaining organic compound selected from the group consisting of meta-bis(l,4,5,6,7,7 hexachlorobicyclo- [2.2.1]-5-hepten-2-yl)benzene, para-bis(1,4,5,6,7,7-hexachlorobicyclo[2.2.1]-5-hepten-2-yl)benzene and mixtures thereof.

8. A composition as claimed in claim 7, wherein the alkenyl aromatic resin is polystyrene.

9. A composition as claimed in claim 7, wherein the alkenyl aromatic resin is a copolymer of styrene and alpha-methyl styrene.

10. A'composit-ion as claimed in claim 7, wherein the alkenyl aromatic resin is a copolymer of from 85 to 98 percent by weight of styrene and from 15 to 2 percent of a rubbery copolymer of butadiene and styrene.

' wherein Ar represents 11. A composition as claimed in claim 7, whereinthe alkenyl aromatic resin isa copolymer of approximately 70 percent 'by weight of styrene and percent of acrylonitrile.

. .12. A composition asiclaimed claim. 7, wherein the" halogen-containing organic compoundis a mixture of metaand para-bis(-191,5,6,7,7-hexachlorobicyclol2.2.11-S- hepten-Z-yDben'Zenemelting at temperatureshctween 150' andISS C. A I '13. A process for making aflame-retardant composi- 10 tion of matter which comprises heat-plastifying and me chanically working with one-another from to pera cent by weight of an alkenyl aromatic resin comprising a solid flammable polymer containing in chemicallycom- ,bined form at least50 percent by; weight of at least one 10 of the benzene series and R represents avmember of the group consisting of hydrogen and the methyl-radical, and

from- 50 to 5 percent by weight of at least one halogencontaining organic compound selected from the group consisting of meta-bis(l,4,5,6,7,7-hexachlorobicyclo- [2.2.1] 5-hepten-2-yl)henzene, v para-bis( 1,4,5,6,7,7-hexa-' chlorobicyclo[2.2.l ]-5-hepten-2-yl)benzene and mixtures thereof, at, temperatures between and 225 C. to

obtain a homogeneous composition.

l4. ;A process as claimed in claim 13, wherein the halogen-containing organic compound is a mixture of metaand para-bis(l,4,5,6,7,7-hexachlorobicyclo[2.2. l]-5-,hepten- '2-yl)ben'zene melting at temperatures between and 15. A process as claimed in claim 13, wherein the alkenyl aromatic resin is polystyrene. Y

References Cited in the file of this patent UNITED STATES PATENTS Herzfeld et al. Aug. 12, 1952 2,-ss3,s4s Robitschek et al. Dec. 9,1958 

1. A FLAME-RETARDANT COMPOSITION OF MATTER COMPRISING AN INTIMATE MIXTURE OF FROM 50 TO 95 PERCENT BY WEIGHT OF AN ALKENYL AROMATIC RESIN COMPRISING A SOLID FLAMMABLE POLYMER CONTAINING IN CHEMICALLY COMBINED FORM AT LEAST 50 PERCENT BY WEIGHT OF AT LEAST ONE ALKENYL AROMATIC COMPOUND HAVING THE GENERAL FORMULA: 